e2fs.c

一个EP9315的redboot,希望对大家有用

                __FUNCTION__, name, namelen, dir_ino);
#endif

    if (!e2fs_get_inode(e2fs, dir_ino, &inode)) {
#if DEBUG_E2FS > 0
	diag_printf("%s: e2fs_get_inode [%d] failed\n", __FUNCTION__, dir_ino);
#endif
	return NULL;
    }

    nbytes = SWAB_LE32(inode.size);
    nblocks = (nbytes + e2fs->blocksize - 1) / e2fs->blocksize;

    last_block_size = nbytes % e2fs->blocksize;
    if (last_block_size == 0)
	last_block_size = e2fs->blocksize;

    for (i = 0; i < nblocks; i++) {
	if (!e2fs_inode_block(e2fs, &inode, i, &block_nr))
	    return NULL;

	if (block_nr) {
	    if (!__READ_BLOCK(block_nr))
		return NULL;
	} else
	    memset(blockbuf, 0, e2fs->blocksize);

	dir = search_dir_block(e2fs, blockbuf, name, namelen);

	if (dir != NULL)
	    return dir;
    }
    return NULL;
}

typedef struct ino_info {
    cyg_uint32  ino;
    cyg_uint32  parent_ino;
    cyg_uint8   filetype;
} ino_info_t;

static int e2fs_inode_lookup(e2fs_desc_t *e2fs, cyg_uint32 dir_ino,
			     const char *pathname, ino_info_t *info);

// Starting from the given directory, find the inode number, filetype, and
// parent inode for the file pointed to by the given symbolic link inode.
// If successful, fills out ino_info_t and return true.
//
static int
e2fs_follow_symlink(e2fs_desc_t *e2fs, cyg_uint32 dir_ino, cyg_uint32 sym_ino, ino_info_t *info)
{
#define MAX_SYMLINK_NAME 255
    char symlink[MAX_SYMLINK_NAME+1];
    int  pathlen;
    cyg_uint32 block_nr;
    e2fs_inode_t inode;

    if (!e2fs_get_inode(e2fs, sym_ino, &inode)) {
#if DEBUG_E2FS > 0
	diag_printf("%s: e2fs_get_inode [%d] failed\n", __FUNCTION__, sym_ino);
#endif
	return 0;
    }

    pathlen = SWAB_LE32(inode.size);
    if (pathlen > MAX_SYMLINK_NAME)
	return 0;

    if (inode.blocks) {
	if (!e2fs_inode_block(e2fs, &inode, 0, &block_nr))
	    return 0;
	if (block_nr) {
	    if (!PARTITION_READ(e2fs->part, E2FS_BLOCK_TO_SECTOR(e2fs, block_nr),
				blockbuf, e2fs->blocksize/SECTOR_SIZE))
		return 0;
	    memcpy(symlink, blockbuf, pathlen);
	} else
	    return 0;
    } else {
	// small enough path to fit in inode struct
	memcpy(symlink, (char *)&inode.block[0], pathlen);
    }
    symlink[pathlen] = 0;

    return e2fs_inode_lookup(e2fs, dir_ino, symlink, info);
}


// Starting from the given directory, find the inode number, filetype, and
// parent inode for the given file pathname.
// If successful, fills out ino_info_t and return true.
//
static int
e2fs_inode_lookup(e2fs_desc_t *e2fs, cyg_uint32 dir_ino, const char *pathname, ino_info_t *info)
{
    int len, pathlen;
    const char *p;
    e2fs_dir_entry_t *dir = NULL;
    
    if (!pathname || (pathlen = strlen(pathname)) == 0)
	return 0;

    if (*pathname == '/') {
	if (--pathlen == 0) {
	    info->ino = info->parent_ino = E2FS_ROOT_INO;
	    info->filetype = E2FS_FTYPE_DIR;
	    return 1;
	}
	++pathname;
	dir_ino = E2FS_ROOT_INO;
    }

    while (pathlen) {
	// find next delimiter in path.
	for (p = pathname, len = 0; len < pathlen; len++, p++) {
	    // skip delimiter if found.
	    if (*p == '/') {
		++p;
		--pathlen;
		break;
	    }
	}
	dir = e2fs_dir_lookup(e2fs, dir_ino, pathname, len);
	if (dir == NULL)
	    return 0;

	pathlen -= len;
	pathname = p;

	switch (dir->filetype) {
	  case E2FS_FTYPE_SYMLINK:
	    // follow the symbolic link (this will cause recursion)
	    if (!e2fs_follow_symlink(e2fs, dir_ino, SWAB_LE32(dir->inode), info))
		return 0;
	    if (pathlen == 0)
		return 1;
	    // must be a dir if we want to continue
            if (info->filetype != E2FS_FTYPE_DIR)
		return 0;
	    dir_ino = info->ino;
	    break;

	  case E2FS_FTYPE_DIR:
	    if (pathlen)
		dir_ino = SWAB_LE32(dir->inode);
	    break;

	  case E2FS_FTYPE_REG_FILE:
	    if (pathlen)
		return 0;  // regular file embedded in middle of path
	    break;

	  case E2FS_FTYPE_UNKNOWN:
	  case E2FS_FTYPE_CHRDEV:
	  case E2FS_FTYPE_BLKDEV:
	  case E2FS_FTYPE_FIFO:
	  case E2FS_FTYPE_SOCK:
	  default:
	    return 0;
	}
    }
    info->ino = SWAB_LE32(dir->inode);
    info->parent_ino = dir_ino;
    info->filetype = dir->filetype;
    return 1;
}

struct read_info {
    e2fs_desc_t  e2fs_desc;
    e2fs_inode_t inode;
    cyg_uint32   fsize;
    cyg_uint32   fpos;
};

static void *
e2fs_open(partition_t *p, const char *filepath)
{
    static struct read_info rinfo;
    ino_info_t    ino_info;

    // mount partition
    if (e2fs_mount(p, &rinfo.e2fs_desc) != 0) {
	diag_printf("mount failed.\n");
	return NULL;
    }

    // find file inode
    if (!e2fs_inode_lookup(&rinfo.e2fs_desc, E2FS_ROOT_INO, filepath, &ino_info)) {
	diag_printf("%s: e2fs_inode_lookup failed\n", __FUNCTION__);
	return NULL;
    }

    // read inode
    if (!e2fs_get_inode(&rinfo.e2fs_desc, ino_info.ino, &rinfo.inode)) {
	diag_printf("%s: e2fs_get_inode failed for ino[%d]\n", __FUNCTION__, ino_info.ino);
	return NULL;
    }

    rinfo.fsize = SWAB_LE32(rinfo.inode.size);
    rinfo.fpos  = 0;

    return &rinfo;
}

static int
e2fs_read(void *fp, char *buf, cyg_uint32 nbytes)
{
    struct read_info *info = fp;
    e2fs_desc_t *e2fs;
    cyg_uint32 nread = 0, rem, block_nr, bindex, to_read;

    if ((info->fpos + nbytes) > info->fsize)
	nbytes = info->fsize - info->fpos;

    e2fs = &info->e2fs_desc;

    // see if we need to copy leftover data from last read call
    rem = e2fs->blocksize - (info->fpos % e2fs->blocksize);
    if (rem != e2fs->blocksize) {
	char *p = (char *)blockbuf + e2fs->blocksize - rem;

	if (rem > nbytes)
	    rem = nbytes;

	memcpy(buf, p, rem);

	nread += rem;
	buf  += rem;
	info->fpos += rem;
    }
    
    // now loop through blocks if we're not done
    bindex = info->fpos / e2fs->blocksize;
    while (nread < nbytes) {
	if (!e2fs_inode_block(e2fs, &info->inode, bindex, &block_nr))
	    return -1;

	if (block_nr) {
	    if (!PARTITION_READ(e2fs->part, E2FS_BLOCK_TO_SECTOR(e2fs, block_nr),
				blockbuf, e2fs->blocksize/SECTOR_SIZE))
		return 0;
	} else
	    memset(blockbuf, 0, e2fs->blocksize);
	
	to_read = nbytes - nread;
	if (to_read > e2fs->blocksize)
	    to_read = e2fs->blocksize;

	memcpy(buf, blockbuf, to_read);

	nread += to_read;
	buf += to_read;
	info->fpos += to_read;
	++bindex;
    }

    return nread;
}

#if DEBUG_E2FS > 4
static void dump_sb(struct e2fs_super_block *s)
{
    diag_printf("inode_count: %d\n", SWAB_LE32(s->inodes_count));
    diag_printf("blocks_count: %d\n", SWAB_LE32(s->blocks_count));
    diag_printf("r_blocks_count: %d\n", SWAB_LE32(s->r_blocks_count));
    diag_printf("free_blocks_count: %d\n", SWAB_LE32(s->free_blocks_count));
    diag_printf("free_inodes_count: %d\n", SWAB_LE32(s->free_inodes_count));
    diag_printf("first_data_block: %d\n", SWAB_LE32(s->first_data_block));
    diag_printf("log_block_size: %d\n", SWAB_LE32(s->log_block_size));
    diag_printf("log_frag_size: %d\n", SWAB_LE32(s->log_frag_size));
    diag_printf("blocks_per_group: %d\n", SWAB_LE32(s->blocks_per_group));
    diag_printf("frags_per_group: %d\n", SWAB_LE32(s->frags_per_group));
    diag_printf("inodes_per_group: %d\n", SWAB_LE32(s->inodes_per_group));
    diag_printf("mnt_count: %d\n", SWAB_LE16(s->mnt_count));
    diag_printf("max_mnt_count: %d\n", SWAB_LE16(s->max_mnt_count));
    diag_printf("magic: %d\n", SWAB_LE16(s->magic));
    diag_printf("state: %d\n", SWAB_LE16(s->state));
    diag_printf("errors: %d\n", SWAB_LE16(s->errors));
    diag_printf("minor_rev_level: %d\n", SWAB_LE16(s->minor_rev_level));
    diag_printf("lastcheck: %d\n", SWAB_LE32(s->lastcheck));
    diag_printf("checkinterval: %d\n", SWAB_LE32(s->checkinterval));
    diag_printf("creator_os: %d\n", SWAB_LE32(s->creator_os));
    diag_printf("rev_level: %d\n", SWAB_LE32(s->rev_level));
}

static void dump_inode(struct e2fs_inode *i)
{
    int j, n;

    diag_printf("mode: %o\n", SWAB_LE16(i->mode));
    diag_printf("uid: %o\n", SWAB_LE16(i->uid));
    diag_printf("size: %d\n", SWAB_LE32(i->size));
    diag_printf("gid: %o\n", SWAB_LE16(i->gid));
    diag_printf("links: %d\n", SWAB_LE16(i->links_count));
    diag_printf("blocks: %d\n", SWAB_LE32(i->blocks));

    n = i->blocks;
    if (n > E2FS_N_BLOCKS)
	n = E2FS_N_BLOCKS;

    for (j = 0; j < n; j++)
	diag_printf("  block: %d\n", SWAB_LE32(i->block[j]));
}
#endif